Three-phase signal generation device; method for generating three-phase signals

Abstract

In one aspect of a three-phase signal generating device according to the present invention: a first complex vector, a second complex vector, and a third complex vector are calculated on the basis of instantaneous values of a first signal, a second signal, and a third signal; in the complex plane, a straight line connecting a vertex of a triangle having, as one side, a straight line connecting a vertex of the first complex vector and a vertex of the second complex vector, to a vertex of the third complex vector is calculated as a first straight line; a straight line connecting a vertex of a triangle having, as one side, a straight line connecting the vertex of the second complex vector and the vertex of the third complex vector, to the vertex of the first complex vector is calculated as a second straight line; a straight line connecting a vertex of a triangle having, as one side, a straight line connecting the vertex of the third complex vector and the vertex of the first complex vector, to the vertex of the second complex vector is calculated as a third straight line; a point of intersection of the first straight line, the second straight line, and the third straight line is calculated; and the first complex vector, the second complex vector, and the third complex vector are corrected by transforming the point of intersection to the origin of the complex plane.

Description

[Technical Field]

[0001] The present invention relates to a three-phase signal generating device and a three-phase signal generating method. This application claims priority to Japanese Patent Application No. 2021-161923, filed on September 30, 2021, the contents of which are incorporated herein by reference. [Background technology]

[0002] Conventionally, motors capable of accurately controlling their rotational position are known to be configured with absolute angular position sensors such as optical encoders and resolvers. However, absolute angular position sensors are large and expensive. Therefore, Patent Document 1 discloses a position estimation method that estimates the rotational position of a motor using three inexpensive and small magnetic sensors without using an absolute angular position sensor. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 6233532 Summary of the Invention [Problem to be solved by the invention]

[0004] The position estimation method described in Patent Document 1 can estimate the mechanical angle of the rotation shaft with high accuracy using three inexpensive and small magnetic sensors, but there has been a demand for higher accuracy from the market. [Means for solving the problem]

[0005] One aspect of the three-phase signal generating device of the present invention includes a first magnetic sensor facing a rotating magnet and outputting a first signal indicating magnetic field strength, a second magnetic sensor facing the magnet and outputting a second signal having a phase delay of 120° electrical angle relative to the first signal, a third magnetic sensor facing the magnet and outputting a third signal having a phase delay of 120° electrical angle relative to the second signal, and a signal processing unit that processes the first signal, the second signal, and the third signal. the signal processing unit includes a first process of digitally converting the first signal, the second signal, and the third signal to obtain an instantaneous value of the first signal, an instantaneous value of the second signal, and an instantaneous value of the third signal; a second process of calculating, based on the instantaneous value of the first signal, the instantaneous value of the second signal, and the instantaneous value of the third signal, a first complex vector that is a complex vector of the first signal, a second complex vector that is a complex vector of the second signal, and a third complex vector that is a complex vector of the third signal; and a third process of calculating, as a first line, a line that connects, in a complex plane, a vertex of a triangle having a line that connects a vertex of the first complex vector and a vertex of the second complex vector as one side. a fourth process of calculating, in the complex plane, a line connecting a vertex of the first complex vector to a vertex of a triangle having, as one side, a line connecting the vertex of the second complex vector to a vertex of the third complex vector; a fifth process of calculating, in the complex plane, a line connecting, as one side, a vertex of the second complex vector to a vertex of a triangle having, as one side, a line connecting the vertex of the third complex vector to a vertex of the first complex vector; a sixth process of calculating an intersection of the first line, the second line, and the third line; and a seventh process of correcting the first complex vector, the second complex vector, and the third complex vector by converting the intersection to the origin of the complex plane.

[0006] One aspect of the three-phase signal generation method of the present invention is a three-phase signal generation method using a first magnetic sensor facing a rotating magnet and outputting a first signal indicating magnetic field strength, a second magnetic sensor facing the magnet and outputting a second signal having a phase delay of 120° in electrical angle relative to the first signal, and a third magnetic sensor facing the magnet and outputting a third signal having a phase delay of 120° in electrical angle relative to the second signal, the method comprising: a first step of acquiring instantaneous values ​​of the first signal, the second signal, and the third signal by digitally converting the first signal, the second signal, and the third signal; a second step of calculating a first complex vector that is a complex vector of the first signal, a second complex vector that is a complex vector of the second signal, and a third complex vector that is a complex vector of the third signal based on the instantaneous values ​​of the first signal, the second signal, and the third signal; and a third step of calculating, as a first line, a line connecting a vertex of the third complex vector with a vertex of a triangle having, as one side, a line connecting the vertex of the first complex vector with a vertex of the second complex vector; a fourth step of calculating, in the complex plane, a second line connecting the vertex of the first complex vector with a vertex of a triangle having, as one side, a line connecting the vertex of the second complex vector with a vertex of the third complex vector; a fifth step of calculating, in the complex plane, a third line connecting the vertex of the second complex vector with a vertex of a triangle having, as one side, a line connecting the vertex of the third complex vector with a vertex of the first complex vector; a sixth step of calculating an intersection of the first line, the second line, and the third line; and a seventh step of correcting the first complex vector, the second complex vector, and the third complex vector by converting the intersection to the origin of the complex plane. [Effects of the Invention]

[0007] According to the above aspects of the present invention, a three-phase signal generating device and a three-phase signal generating method are provided that can improve the estimation accuracy (detection accuracy) of the mechanical angle of the rotating shaft. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a block diagram that schematically shows the configuration of a three-phase signal generator 1 according to one embodiment of the present invention. [Figure 2] FIG. 2 is a diagram showing an example of waveforms of the U-phase sensor signal Hu, the V-phase sensor signal Hv, and the W-phase sensor signal Hw. [Figure 3] FIG. 3 is an enlarged view of the U-phase sensor signal Hu, the V-phase sensor signal Hv, and the W-phase sensor signal Hw included in one pole pair region shown in FIG. [Figure 4] FIG. 4 is a diagram showing an example of waveforms of the sensor signals Hu, Hv, and Hw including an in-phase signal that is a noise component. [Figure 5] FIG. 5 is a diagram showing an example of waveforms of the sensor signals Hiu0, Hiv0, and Hiw0 obtained after the first correction process is performed. [Figure 6] FIG. 6 is a diagram showing an example of waveforms of the sensor signals Hiu1, Hiv1, and Hiw1 obtained after the second correction process is performed. [Figure 7] FIG. 7 is a diagram showing an example of waveforms of the sensor signals Hiu2, Hiv2, and Hiw2 obtained after the third correction process is performed. [Figure 8] FIG. 8 is a flowchart showing a three-phase signal generation process executed by the processing unit 21 of the three-phase signal generator 1 in this embodiment. [Figure 9] FIG. 9 is a complex plane diagram used to explain the processing of steps S1 and S2 included in the three-phase signal generation processing. [Figure 10] FIG. 10 is a complex plane diagram used to explain the processes from step S3 to step S6 included in the three-phase signal generation process. [Figure 11] FIG. 11 is a complex plane diagram used to explain the processing of step S7 included in the three-phase signal generation processing. [Figure 12] FIG. 12 is a first diagram showing a simulation result of three-phase signals obtained by the three-phase signal generation process. [Figure 13]FIG. 13 is a second diagram showing the simulation results of the three-phase signals obtained by the three-phase signal generation process. DETAILED DESCRIPTION OF THE INVENTION

[0009] An embodiment of the present invention will be described in detail below with reference to the drawings. FIG. 1 is a block diagram schematically showing the configuration of a three-phase signal generator 1 according to an embodiment of the present invention. As shown in FIG. 1, the three-phase signal generator 1 is a device that detects the mechanical angle (rotation angle) of a rotor shaft 110, which is the rotating shaft of a motor 100. In this embodiment, the motor 100 is, for example, an inner rotor type three-phase brushless DC motor. The motor 100 has the rotor shaft 110 and a sensor magnet 120.

[0010] The sensor magnet 120 is a disk-shaped magnet attached to the rotor shaft 110. The sensor magnet 120 rotates in synchronization with the rotor shaft 110. The sensor magnet 120 has P magnetic pole pairs (P is an integer equal to or greater than 1). In this embodiment, as an example, the sensor magnet 120 has four magnetic pole pairs. Note that a magnetic pole pair refers to a pair of an N pole and an S pole. That is, in this embodiment, the sensor magnet 120 has four pairs of an N pole and an S pole, for a total of eight magnetic poles.

[0011] The three-phase signal generator 1 includes a sensor group 10 and a signal processing unit 20. Although not shown in FIG. 1 , a circuit board is attached to the motor 100, and the sensor group 10 and signal processing unit 20 are arranged on the circuit board. The sensor magnet 120 is arranged in a position that does not interfere with the circuit board. The sensor magnet 120 may be arranged inside the housing of the motor 100 or outside the housing.

[0012] The sensor group 10 includes a first magnetic sensor 11, a second magnetic sensor 12, and a third magnetic sensor 13. The first magnetic sensor 11, the second magnetic sensor 12, and the third magnetic sensor 13 are arranged on the circuit board facing the sensor magnet 120. In this embodiment, the first magnetic sensor 11, the second magnetic sensor 12, and the third magnetic sensor 13 are arranged on the circuit board at 30° intervals along the rotation direction of the sensor magnet 120. For example, the first magnetic sensor 11, the second magnetic sensor 12, and the third magnetic sensor 13 are each an analog output type magnetic sensor including a magnetoresistive element, such as a Hall element or a linear Hall IC. The first magnetic sensor 11, the second magnetic sensor 12, and the third magnetic sensor 13 each output an analog signal indicating a magnetic field strength that changes depending on the rotational position of the rotor shaft 110, i.e., the rotational position of the sensor magnet 120.

[0013] One electrical angle cycle of the analog signals output from the first magnetic sensor 11, the second magnetic sensor 12, and the third magnetic sensor 13 corresponds to 1 / P of one mechanical angle cycle. In this embodiment, since the number of pole pairs P of the sensor magnet 120 is "4," one electrical angle cycle of each analog signal corresponds to 1 / 4 of one mechanical angle cycle, or 90° mechanical angle. The analog signal output from the second magnetic sensor 12 has a phase delay of 120° electrical angle with respect to the analog signal output from the first magnetic sensor 11. The analog signal output from the third magnetic sensor 13 has a phase delay of 120° electrical angle with respect to the analog signal output from the second magnetic sensor 12.

[0014] Hereinafter, the analog signal output from the first magnetic sensor 11 will be referred to as the U-phase sensor signal Hu, the analog signal output from the second magnetic sensor 12 will be referred to as the V-phase sensor signal Hv, and the analog signal output from the third magnetic sensor 13 will be referred to as the W-phase sensor signal Hw.

[0015] The first magnetic sensor 11 faces a sensor magnet 120, which is a rotating magnet, and outputs a U-phase sensor signal Hu (first signal) indicating magnetic field strength to the signal processing unit 20. The second magnetic sensor 12 faces the sensor magnet 120, and outputs a V-phase sensor signal Hv (second signal) having a phase delay of 120° in electrical angle with respect to the U-phase sensor signal Hu to the signal processing unit 20. The third magnetic sensor 13 faces the sensor magnet 120, and outputs a W-phase sensor signal Hw (third signal) having a phase delay of 120° in electrical angle with respect to the V-phase sensor signal Hv to the signal processing unit 20.

[0016] The signal processing unit 20 is a signal processing circuit that processes the U-phase sensor signal Hu, the V-phase sensor signal Hv, and the W-phase sensor signal Hw. The signal processing unit 20 estimates the mechanical angle of the rotor shaft 110, which is the rotation axis, based on the U-phase sensor signal Hu, the V-phase sensor signal Hv, and the W-phase sensor signal Hw. The signal processing unit 20 includes a processing unit 21 and a storage unit 22.

[0017] The processing unit 21 is a microprocessor such as an MCU (Microcontroller Unit). The U-phase sensor signal Hu, the V-phase sensor signal Hv, and the W-phase sensor signal Hw are each input to the processing unit 21. The processing unit 21 is communicably connected to the storage unit 22 via a communication bus (not shown). The processing unit 21 executes at least the following two processes in accordance with a program stored in advance in the storage unit 22.

[0018] The processing unit 21 performs offline processing based on the U-phase sensor signal Hu, the V-phase sensor signal Hv, and the W-phase sensor signal Hw. Then, a learning process is performed to acquire learning data required for estimating the mechanical angle of the rotor shaft 110. The offline process is a process that is performed before the three-phase signal generator 1 is shipped from a manufacturing factory or before the three-phase signal generator 1 is incorporated into a customer's system and put into actual operation.

[0019] Furthermore, the processing unit 21 performs an angle estimation process as online processing to estimate the mechanical angle of the rotor shaft 110 based on the U-phase sensor signal Hu, the V-phase sensor signal Hv, and the W-phase sensor signal Hw and learning data obtained by the learning process. The online processing is processing that is executed when the three-phase signal generating device 1 is incorporated into a customer's system and put into actual operation.

[0020] The storage unit 22 includes a nonvolatile memory that stores programs, various setting data, the above-mentioned learning data, and the like required for the processing unit 21 to execute various processes, and a volatile memory that is used as a temporary storage destination for data when the processing unit 21 executes various processes. The nonvolatile memory is, for example, an EEPROM (Electrically Erasable Programmable Read-Only Memory) or a flash memory. The volatile memory is, for example, a RAM (Random Access Memory).

[0021] Before describing the learning process and angle estimation process executed by the processing unit 21 of the three-phase signal generator 1 configured as described above, a brief description of the position estimation method disclosed in Japanese Patent No. 6233532 will be given below to facilitate understanding of the present invention. In the following description, the position estimation method disclosed in Japanese Patent No. 6233532 may be referred to as the basic patent method. For details of the basic patent method, please refer to Japanese Patent No. 6233532. For convenience of explanation, the basic patent method will be described below using the elements shown in FIG. 1.

[0022] First, we will explain the learning process executed by the processing unit 21 in the basic patent method. The processing unit 21 acquires instantaneous values ​​(digital values) of the sensor signals Hu, Hv, and Hw output from the magnetic sensors 11, 12, and 13 while the sensor magnet 120 is rotating together with the rotor shaft 110. Specifically, the processing unit 21 has a built-in A / D converter, and the processing unit 21 acquires the instantaneous values ​​of the U-phase sensor signal Hu, the V-phase sensor signal Hv, and the W-phase sensor signal Hw by digitally converting the U-phase sensor signal Hu, the V-phase sensor signal Hv, and the W-phase sensor signal Hw using the A / D converter at a predetermined sampling frequency.

[0023] During the learning process, the rotor shaft 110 may be rotated by controlling the supply of current to the motor 100 via a motor control device (not shown). Alternatively, the rotor shaft 110 may be connected to a rotating machine (not shown) and rotated by the rotating machine.

[0024] FIG. 2 is a diagram showing an example of the waveforms of the U-phase sensor signal Hu, the V-phase sensor signal Hv, and the W-phase sensor signal Hw. As shown in FIG. 2, one electrical cycle of each of the sensor signals Hu, Hv, and Hw corresponds to ¼ of one mechanical cycle, i.e., 90° mechanical angle. In FIG. 2, the period from time t1 to time t5 corresponds to one mechanical cycle (360° mechanical angle). In FIG. 2, the period from time t1 to time t2, the period from time t2 to time t3, the period from time t3 to time t4, and the period from time t4 to time t5 each correspond to 90° mechanical angle. Furthermore, the sensor signals Hu, Hv, and Hw have a phase difference of 120° electrical angle from one another.

[0025] Based on the digital values ​​of the sensor signals Hu, Hv, and Hw, the processing unit 21 extracts, over one mechanical angle cycle, intersection points where two of the three sensor signals intersect with each other and zero-crossing points where each of the three sensor signals intersects with a reference signal level. The reference signal level is, for example, ground level. When the reference signal level is ground level, the digital value of the reference signal level is "0."

[0026] As shown in FIG. 2, the processing unit 21 divides one mechanical angle cycle into four pole pair regions associated with pole pair numbers based on the result of extracting the zero-crossing points. In FIG. 2, "No. C" indicates the pole pair number. As shown in FIG. 1, pole pair numbers are assigned in advance to the four magnetic pole pairs of the sensor magnet 120. For example, the pole pair number "0" is assigned to the magnetic pole pair located in the mechanical angle range of 0° to 90°. The pole pair number "1" is assigned to the magnetic pole pair located in the mechanical angle range of 90° to 180°. The pole pair number "2" is assigned to the magnetic pole pair located in the mechanical angle range of 180° to 270°. The pole pair number "3" is assigned to the magnetic pole pair located in the mechanical angle range of 270° to 360°.

[0027] For example, when the sensor signal Hu is used as a reference, the processing unit 21 recognizes, among the zero-crossing points of the sensor signal Hu, the zero-crossing point obtained at the sampling timing (time t1) when the mechanical angle is 0° as the start point of the pole pair region associated with the pole pair number "0". Furthermore, the processing unit 21 recognizes, among the zero-crossing points of the sensor signal Hu, the zero-crossing point obtained at the sampling timing (time t2) when the mechanical angle is 90° as the end point of the pole pair region associated with the pole pair number "0". In other words, the processing unit 21 determines the section between the zero-crossing point obtained at time t1 and the zero-crossing point obtained at time t2 as the pole pair region associated with the pole pair number "0".

[0028] The processing unit 21 recognizes, among the zero-crossing points of the sensor signal Hu, the zero-crossing point obtained at the sampling timing (time t2) when the mechanical angle is 90° as the start point of the pole pair region associated with the pole pair number "1". Furthermore, the processing unit 21 recognizes, among the zero-crossing points of the sensor signal Hu, the zero-crossing point obtained at the sampling timing (time t3) when the mechanical angle is 180° as the end point of the pole pair region associated with the pole pair number "1". In other words, the processing unit 21 determines the section between the zero-crossing point obtained at time t2 and the zero-crossing point obtained at time t3 as the pole pair region associated with the pole pair number "1".

[0029] The processing unit 21 recognizes, among the zero crossing points of the sensor signal Hu, the zero crossing point obtained at the sampling timing (time t3) when the mechanical angle is 180° as the start point of the pole pair region associated with the pole pair number "2". Furthermore, the processing unit 21 recognizes, among the zero crossing points of the sensor signal Hu, the zero crossing point obtained at the sampling timing (time t4) when the mechanical angle is 270° as the end point of the pole pair region associated with the pole pair number "2". In other words, the processing unit 21 determines the section between the zero crossing point obtained at time t3 and the zero crossing point obtained at time t4 as the pole pair region associated with the pole pair number "2".

[0030] The processing unit 21 recognizes, among the zero crossing points of the sensor signal Hu, the zero crossing point obtained at the sampling timing (time t4) when the mechanical angle is 270° as the start point of the pole pair region associated with the pole pair number "3". Furthermore, the processing unit 21 recognizes, among the zero crossing points of the sensor signal Hu, the zero crossing point obtained at the sampling timing (time t5) when the mechanical angle is 360° as the end point of the pole pair region associated with the pole pair number "3". In other words, the processing unit 21 determines the section between the zero crossing point obtained at time t4 and the zero crossing point obtained at time t5 as the pole pair region associated with the pole pair number "3".

[0031] As shown in Fig. 2, the processing unit 21 divides each of the four pole pair regions into 12 sections associated with section numbers based on the extraction results of the intersections and zero crossing points. In Fig. 2, "No. A" indicates the section number associated with each section. As shown in Fig. 2, the 12 sections included in each of the four pole pair regions are associated with section numbers from "0" to "11."

[0032] 3 is an enlarged view of the sensor signals Hu, Hv, and Hw included in one pole pair region shown in FIG. 2. In FIG. 3, the reference value (reference signal level) of the amplitude is "0." In FIG. 3, the digital value of the amplitude that is a positive value represents, as an example, the digital value of the magnetic field strength of the north pole. Also, the digital value of the amplitude that is a negative value represents, as an example, the digital value of the magnetic field strength of the south pole.

[0033] 3, points P1, P3, P5, P7, P9, P11, and P13 are zero-crossing points extracted from the digital values ​​of the sensor signals Hu, Hv, and Hw included in one pole pair region. Also, in FIG. 3, points P2, P4, P6, P8, P10, and P12 are intersections extracted from the digital values ​​of the sensor signals Hu, Hv, and Hw included in one pole pair region. As shown in FIG. 3, the processing unit 21 determines the intervals between adjacent zero-crossing points and intersections as sections.

[0034] The processing unit 21 determines the section between zero cross point P1 and intersection point P2 as the section associated with section number "0." The processing unit 21 determines the section between intersection point P2 and zero cross point P3 as the section associated with section number "1." The processing unit 21 determines the section between zero cross point P3 and intersection point P4 as the section associated with section number "2." The processing unit 21 determines the section between intersection point P4 and zero cross point P5 as the section associated with section number "3." The processing unit 21 determines the section between zero cross point P5 and intersection point P6 as the section associated with section number "4." The processing unit 21 determines the section between intersection point P6 and zero cross point P7 as the section associated with section number "5."

[0035] The processing unit 21 determines the section between zero cross point P7 and intersection point P8 as the section associated with section number "6." The processing unit 21 determines the section between intersection point P8 and zero cross point P9 as the section associated with section number "7." The processing unit 21 determines the section between zero cross point P9 and intersection point P10 as the section associated with section number "8." The processing unit 21 determines the section between intersection point P10 and zero cross point P11 as the section associated with section number "9." The processing unit 21 determines the section between zero cross point P11 and intersection point P12 as the section associated with section number "10." The processing unit 21 determines the section between intersection point P12 and zero cross point P13 as the section associated with section number "11."

[0036] In the following description, for example, a section assigned section number "0" will be referred to as "section 0," and a section assigned section number "11" will be referred to as "section 11."

[0037] As shown in FIG. 2, consecutive numbers throughout one mechanical angle cycle are associated with each section number as segment numbers. In FIG. 2, "No. B" indicates the segment number associated with each section number. Note that the term "segment" refers to a line connecting adjacent intersections and zero-crossing points. In other words, a line connecting the start and end points of each section is called a segment. In FIG. 3, for example, the start point of section 0 is zero-crossing point P1, and the end point of section 0 is intersection point P2. Therefore, the segment corresponding to section 0 is the line connecting zero-crossing point P1 and intersection point P2. Similarly, in FIG. 3, for example, the start point of section 1 is intersection point P2, and the end point of section 1 is zero-crossing point P3. Therefore, the segment corresponding to section 1 is the line connecting intersection point P2 and zero-crossing point P3.

[0038] As shown in Figure 2, in the pole pair area associated with pole pair number "0", segment numbers "0" to "11" are associated with section numbers "0" to "11". In the pole pair area associated with pole pair number "1", segment numbers "12" to "23" are associated with section numbers "0" to "11". In the pole pair area associated with pole pair number "2", segment numbers "13" to "23" are associated with section numbers "0" to "11". Segment numbers "24" to "35" are associated with section numbers "0" to "11." In the pole pair area associated with pole pair number "3," segment numbers "36" to "47" are associated with section numbers "0" to "11."

[0039] In the following description, for example, a segment assigned segment number "0" will be referred to as "segment no. 1," and a segment assigned segment number "11" will be referred to as "segment no. 11."

[0040] The processing unit 21 generates a linear function θ(Δx) that represents each segment. Δx is the length (digital value) from the start point of the segment to an arbitrary point on the segment, and θ is the mechanical angle corresponding to the arbitrary point on the segment. In FIG. 3, for example, the start point of the segment corresponding to section 0 is zero-crossing point P1, and the end point of the segment corresponding to section 0 is intersection point P2. Similarly, in FIG. 3, for example, the start point of the segment corresponding to section 1 is intersection point P2, and the end point of the segment corresponding to section 1 is zero-crossing point P3.

[0041] For example, a linear function θ(Δx) representing a segment is expressed by the following equation (1): In the following equation (1), "i" is the segment number and is an integer from 0 to 47. In the following description, the linear function θ(Δx) expressed by the following equation (1) may be referred to as a mechanical angle estimation equation, and the mechanical angle θ calculated by the following equation (1) may be referred to as a mechanical angle estimated value. θ(Δx)=k[i]×Δx+θres[i] …(1)

[0042] In the above equation (1), k[i] is a coefficient called a normalization coefficient. In other words, k[i] is a coefficient that represents the slope of the i-th segment. The normalization coefficient k[i] is expressed by the following equation (2). In the following equation (2), ΔXnorm[i] is the deviation of the digital values ​​between the start point and end point of the i-th segment. In FIG. 3, for example, ΔXnorm[i] of the segment corresponding to section 0 is the deviation of the digital values ​​between zero-crossing point P1 and intersection point P2. Similarly, in FIG. 3, for example, ΔXnorm[i] of the segment corresponding to section 1 is the deviation of the digital values ​​between intersection point P2 and zero-crossing point P3. k[i]=θnorm[i] / ΔXnorm[i] …(2)

[0043] In the above equation (2), θnorm[i] is the deviation in mechanical angle between the start point and end point of the i-th segment, and is expressed by the following equation (3): In the below equation (3), t[i] is the time between the start point and end point of the i-th segment, t[0] is the time between the start point and end point of the 0-th segment, and t

[47] is the time between the start point and end point of the 47-th segment. In Figure 3, for example, if the segment corresponding to the 0-th segment is the 0-th segment, t[0] is the time between the zero-crossing point P1 and the intersection point P2. θnorm[i]={t[i] / (t[0]+…+t

[47] )}×360[degM] …(3)

[0044] In the above equation (1), θres[i] is a constant (the intercept of the linear function θ(Δx)) called the angle reset value of the i-th segment. When the segment number "i" is "0", the angle reset value θres[i] is expressed by the following equation (4). When the segment number "i" is any value from "1" to "47", the angle reset value θres[i] is expressed by the following equation (5). Note that instead of calculating θnorm[i] from t[i] as described above, it may also be calculated from the true mechanical angle (for example, the mechanical angle indicated by the output signal of an encoder attached to the rotor shaft 110). θres[i]=0[degM] …(4) θres[i]=Σ(θnorm[i-1]) …(5)

[0045] By performing the learning process described above, the processing unit 21 acquires the correspondence between pole pair numbers, section numbers, and segment numbers, characteristic data for each section, and the mechanical angle estimation formula for each segment, and stores this acquired data as learning data in the memory unit 22. Note that the characteristic data for each section refers to the magnitude relationship and positive / negative signs of the digital values ​​of the sensor signals Hu, Hv, and Hw included in each section. In addition, the normalization coefficient k[i] and angle reset value θres[i] that constitute the mechanical angle estimation formula for each segment are stored in the memory unit 22 as learning data.

[0046] Next, we will explain the angle estimation process executed by the processing unit 21 in the basic patent method. The processing unit 21 acquires the sensor signals Hu, Hv, and Hw output from the magnetic sensors 11, 12, and 13. Specifically, the processing unit 21 acquires digital values ​​of the U-phase sensor signal Hu, the V-phase sensor signal Hv, and the W-phase sensor signal Hw by digitally converting each of the U-phase sensor signal Hu, the V-phase sensor signal Hv, and the W-phase sensor signal Hw at a predetermined sampling frequency using an A / D converter.

[0047] The processing unit 21 then identifies the current section number and pole pair number based on the digital values ​​of the sensor signals Hu, Hv, and Hw obtained at the current sampling timing. For example, in FIG. 3, assume that point PHu located on the waveform of the U-phase sensor signal Hu, point PHv located on the waveform of the V-phase sensor signal Hv, and point PHw located on the waveform of the W-phase sensor signal Hw are the digital values ​​of the sensor signals Hu, Hv, and Hw obtained at the current sampling timing. The processing unit 21 identifies the current section (section number) by comparing feature data, such as the magnitude relationship and positive / negative signs of the digital values ​​of points PHu, PHv, and PHw, with feature data of each section included in the learning data stored in the memory unit 22. In the example of FIG. 3, section 9 is identified as the current section. Note that a method for identifying pole pair numbers will not be described in this specification. For details on the method for identifying pole pair numbers, see Japanese Patent No. 6233532. Assume, for example, that pole pair number "2" is identified as the pole pair number at the current sampling timing.

[0048] Then, the processing unit 21 identifies the current segment number based on the identified current section number and pole pair number. For example, the processing unit 21 identifies the current segment number using the formula "segment number = 12 × pole pair number + section number." Assuming that the section number "9" is identified as the current section number and the pole pair number "2" is identified as the current pole pair number as described above, the processing unit 21 identifies the segment number "33" as the current segment number (see FIG. 2).

[0049] The processing unit 21 reads out the normalization coefficient k[i] and angle reset value θres[i] corresponding to the identified segment number "i" from the learning data stored in the memory unit 22, and calculates the estimated mechanical angle θ using the mechanical angle estimation formula expressed by the above equation (1). Here, the digital value of the sensor signal corresponding to the identified segment is used as Δx to be substituted into the mechanical angle estimation formula. For example, as described above, if segment number "33" is identified as the current segment number, the processing unit 21 reads out the normalization coefficient k

[33] and angle reset value θres

[33] from the memory unit 22, and substitutes the digital value of point PHv (see FIG. 3) into the mechanical angle estimation formula as Δx, thereby calculating the estimated mechanical angle θ at the current sampling timing.

[0050] The above is the basic procedure for estimating the mechanical angle in the basic patent method that forms the basis of this invention. In the basic patent method, correction processing is performed on the sensor signals Hu, Hv, and Hw to improve the accuracy of the mechanical angle estimation (the accuracy of the estimated mechanical angle value θ). For example, as shown in Figure 2, the amplitude values ​​of the sensor signals Hu, Hv, and Hw do not necessarily match. Furthermore, as shown in Figure 4, the sensor signals Hu, Hv, and Hw may contain in-phase signals (such as DC signals and third-order harmonic signals) that are noise components. Figure 4 shows an example of the waveforms of the sensor signals Hu, Hv, and Hw that contain in-phase signals that are noise components. In Figure 4, the vertical axis represents the digital value, and the horizontal axis represents the electrical angle.

[0051] Therefore, when the processing unit 21 in the basic patent method acquires the digital values ​​of the sensor signals Hu, Hv, and Hw during the execution of the learning process and the angle estimation process, it first executes a first correction process to remove in-phase signals from the sensor signals Hu, Hv, and Hw based on the following equations (6), (7), and (8). Hiu0=Hu-(Hv+Hw) / 2 …(6) Hiv0 = Hv - (Hu + Hw) / 2 ... (7) Hiw0=Hw-(Hu+Hv) / 2 …(8)

[0052] In equation (6), Hiu0 is the digital value of the U-phase sensor signal obtained by performing the first correction process on the U-phase sensor signal Hu. In equation (7), Hiv0 is the digital value of the V-phase sensor signal obtained by performing the first correction process on the V-phase sensor signal Hv. In equation (8), Hiw0 is the digital value of the W-phase sensor signal obtained by performing the first correction process on the W-phase sensor signal Hw. FIG. 5 is a diagram showing an example of the waveforms of the sensor signals Hiu0, Hiv0, and Hiw0 obtained after the first correction process is performed. In FIG. 5, the vertical axis represents the digital value, and the horizontal axis represents the electrical angle.

[0053] After performing the first correction process, the processing unit 21 in the basic patent method performs a second correction process to match the amplitude values ​​of the sensor signals Hiu0, Hiv0, and Hiw0 based on the following equations (9) to (14): Hiu1(ppn)=au_max(ppn)×Hiu0(ppn)+bu…(9) Hiu1(ppn)=au_min(ppn)×Hiu0(ppn)+bu…(10) Hiv1(ppn)=av_max(ppn)×Hiv0(ppn)+bv …(11) Hiv1(ppn)=av_min(ppn)×Hiv0(ppn)+bv …(12) Hiw1(ppn)=aw_max(ppn)×Hiw0(ppn)+bw …(13) Hiw1(ppn)=aw_min(ppn)×Hiw0(ppn)+bw …(14)

[0054] The processing unit 21 performs a second correction process on the positive digital value of the U-phase sensor signal Hiu0 using the information stored in the storage unit 22, according to the above equation (9). The processing unit 21 also performs a second correction process on the negative digital value of the U-phase sensor signal Hiu0 using the information stored in the storage unit 22, according to the above equation (10). The processing unit 21 also performs a second correction process on the positive digital value of the V-phase sensor signal Hiv0 using the information stored in the storage unit 22, according to the above equation (11). The processing unit 21 also performs a second correction process on the negative digital value of the V-phase sensor signal Hiv0 using the information stored in the storage unit 22, according to the above equation (12). The processing unit 21 also performs a second correction process on the positive digital value of the W-phase sensor signal Hiw0 using the information stored in the storage unit 22, according to the above equation (13). Furthermore, the processing unit 21 performs a second correction process on the negative digital value of the W-phase sensor signal Hiw0 using the information stored in the storage unit 22 and the above equation (14).

[0055] In equations (9) and (10), Hiu1 is the digital value of the U-phase sensor signal obtained by performing the second correction process on the U-phase sensor signal Hiu0. In equations (11) and (12), Hiv1 is the digital value of the V-phase sensor signal obtained by performing the second correction process on the V-phase sensor signal Hiv0. In equations (13) and (14), Hiw1 is the digital value of the W-phase sensor signal obtained by performing the second correction process on the W-phase sensor signal Hiw0. FIG. 6 is a diagram showing an example of the waveforms of the sensor signals Hiu1, Hiv1, and Hiw1 obtained after the second correction process is performed. In FIG. 6, the vertical axis represents the digital value, and the horizontal axis represents the electrical angle.

[0056] In equations (9) to (14), ppn is a pole pair number ranging from 0 to 3. In equations (9), (11), and (13), au_max(ppn), av_max(ppn), and aw_max(ppn) are positive-side gain correction values ​​for the positive digital values ​​for one electrical cycle corresponding to each magnetic pole pair, which are pre-stored in the storage unit 22. In equations (10), (12), and (14), au_min(ppn), av_min(ppn), and aw_min(ppn) are negative-side gain correction values ​​for the negative digital values ​​for one electrical cycle corresponding to each magnetic pole pair, which are pre-stored in the storage unit 22. In equations (9) to (14), bu, bv, and bw are offset correction values ​​for each phase, which are pre-stored in the storage unit 22. Note that au_max(ppn), av_max(ppn), aw_max(ppn), au_min(ppn), av_min(ppn), and aw_min(ppn) are correction values ​​for each pole pair. Therefore, the number of positive-side gain correction values ​​is 12 (= 3 phases × 4 number of pole pairs). Similarly, the number of negative-side gain correction values ​​is 12.

[0057] After performing the second correction process, the processing unit 21 in the basic patent method performs a third correction process on the sensor signals Hiu1, Hiv1, and Hiw1 to linearize portions (divided signals) of the sensor signals corresponding to each segment. In Fig. 3, for example, if the segment corresponding to section 0 is segment 0, the divided signal corresponding to segment 0 is the signal of the portion of the U-phase sensor signal Hu connecting zero-cross point P1 and intersection point P2. Similarly, in Fig. 3, for example, if the segment corresponding to section 1 is segment 1, the divided signal corresponding to segment 1 is the signal of the portion of the W-phase sensor signal Hw connecting intersection point P2 and zero-cross point P3.

[0058] The processing unit 21 performs a third correction process on the sensor signals Hiu1, Hiv1, and Hiw1, changing the scale of each sensor signal by using values ​​pre-stored in the storage unit 22 as coefficients. By performing the third correction process, the approximately S-shaped shapes of the divided signals corresponding to each segment can be linearized. Here, the values ​​stored in the storage unit 22 are pre-designed values. This third correction process performs calculations using pre-designed values ​​and a correction formula such as a quadratic function, a cubic function, or a trigonometric function.

[0059] As an example, the processing unit 21 performs the third correction process on the sensor signals Hiu1, Hiv1, and Hiw1 based on the following equations (15) to (17): In the following equations (15) to (17), a and b are coefficients pre-stored in the storage unit 22. Hiu2=b×tan(a×Hiu1) …(15) HIV2=b×tan(a×HIV1) …(16) Hiw2=b×tan(a×Hiw1) …(17)

[0060] In equation (15), Hiu2 is the digital value of the U-phase sensor signal obtained by performing the third correction process on the U-phase sensor signal Hiu1. In equation (16), Hiv2 is the digital value of the V-phase sensor signal obtained by performing the third correction process on the V-phase sensor signal Hiv1. In equation (17), Hiw2 is the digital value of the W-phase sensor signal obtained by performing the third correction process on the W-phase sensor signal Hiw1. FIG. 7 is a diagram showing an example of the waveforms of the sensor signals Hiu2, Hiv2, and Hiw2 obtained after the third correction process is performed. In FIG. 7, the vertical axis represents the digital value, and the horizontal axis represents the electrical angle.

[0061] As described above, the basic patent method can reduce common-mode noise contained in the sensor signals Hu, Hv, and Hw through the first correction process. Furthermore, the basic patent method can correct for inter-sensor signal variations through the second correction process. Here, inter-sensor signal variations include, for example, variations in the amplitude and offset components of each sensor signal. Furthermore, the basic patent method can linearize the curved portions (divided signals) of the waveforms of each sensor signal through the third correction process. In particular, the second correction process equalizes the lengths of the curved portions of the sensor signals corresponding to the segments, making it easier to apply a uniform calculation process to all divided signals in the third correction process. Therefore, by performing the second correction process before the third correction process, the curved portions (divided signals) of the waveforms can be more linearized. As a result, the basic patent method further linearizes the divided signals required for calculating the estimated mechanical angle θ based on the above equation (1), thereby reducing the difference between the estimated mechanical angle θ and the true mechanical angle, thereby enabling highly accurate mechanical angle estimation.

[0062] As described above, the basic patent method can reduce the common-mode noise contained in each sensor signal Hu, Hv, and Hw through the first correction process. However, although the sensor signals Hiu0, Hiv0, and Hiw0 obtained after the first correction process ideally have a phase difference of 120 degrees electrical angle relative to each other, the phase difference between the sensor signals Hiu0, Hiv0, and Hiw0 may not be exactly 120 degrees because the common-mode noise is reduced using the above equations (6), (7), and (8). Furthermore, the basic patent method can linearize the curved portions of the waveforms of each sensor signal through the third correction process. However, since the third correction process uses table data to perform the calculations expressed by the above equations (15), (16), and (17), errors may occur depending on the position of the divided signals because the same table data is used for all curved portions (divided signals).

[0063] The present invention aims to further reduce the angle error between the estimated mechanical angle θ and the true mechanical angle, compared to the above-mentioned basic patent method, thereby improving the accuracy of detecting the mechanical angle of a rotating shaft.

[0064] Hereinafter, a three-phase signal generation process executed by the processing unit 21 of the three-phase signal generator 1 in this embodiment to solve the above technical problems will be described.

[0065] Fig. 8 is a flowchart showing a three-phase signal generation process executed by the processing unit 21 of the three-phase signal generator 1 in this embodiment. The processing unit 21 executes the three-phase signal generation process shown in Fig. 8 before executing the learning process of the basic patent method described above. More specifically, the processing unit 21 executes the three-phase signal generation process before executing the third correction process, without executing the first correction process and the second correction process.

[0066] 8, while the sensor magnet 120 is rotating together with the rotor shaft 110, the processing unit 21 acquires instantaneous values ​​(digital values) of the sensor signals Hu, Hv, and Hw output from the magnetic sensors 11, 12, and 13 (step S1). This step S1 corresponds to the first step, and the processing executed in step S1 corresponds to the first processing. Hereinafter, the instantaneous value of the U-phase sensor signal Hu will be represented by Hu0(t), the instantaneous value of the V-phase sensor signal Hv will be represented by Hv0(t), and the instantaneous value of the W-phase sensor signal Hw will be represented by Hw0(t).

[0067] Next, based on the instantaneous value Hu0(t) of the U-phase sensor signal Hu, the instantaneous value Hv0(t) of the V-phase sensor signal Hv, and the instantaneous value Hw0(t) of the W-phase sensor signal Hw, the processing unit 21 calculates a U-phase complex vector (first complex vector) that is the complex vector of the U-phase sensor signal Hu, a V-phase complex vector (second complex vector) that is the complex vector of the V-phase sensor signal Hv, and a W-phase complex vector (third complex vector) that is the complex vector of the W-phase sensor signal Hw (step S2). This step S2 corresponds to the second step, and the processing executed in step S2 corresponds to the second processing. Hereinafter, the U-phase complex vector will be represented by Hu1(t), the V-phase complex vector by Hv1(t), and the W-phase complex vector by Hw1(t).

[0068] 9 is a diagram showing the instantaneous value Hu0(t) of the U-phase sensor signal Hu, the instantaneous value Hv0(t) of the V-phase sensor signal Hv, the instantaneous value Hw0(t) of the W-phase sensor signal Hw, the U-phase complex vector Hu1(t), the V-phase complex vector Hv1(t), and the W-phase complex vector Hw1(t) as vectors on the complex plane. In FIG. 9, the horizontal axis is the real axis and the vertical axis is the imaginary axis. The U-phase complex vector Hu1(t), the V-phase complex vector Hv1(t), and the W-phase complex vector Hw1(t) are vectors that rotate at an angular velocity ω(t) in the direction of the arrows on the complex plane. The instantaneous value Hu0(t) of the U-phase sensor signal Hu, the instantaneous value Hv0(t) of the V-phase sensor signal Hv, and the instantaneous value Hw0(t) of the W-phase sensor signal Hw are vectors whose absolute value (norm) and sign (vector direction) change on the real axis.

[0069] Although not shown in Figure 9, the instantaneous value Hu0(t) of the U-phase sensor signal Hu, the instantaneous value Hv0(t) of the V-phase sensor signal Hv, and the instantaneous value Hw0(t) of the W-phase sensor signal Hw are each expressed as a composite vector of a fundamental signal and an in-phase signal. The in-phase signal is a noise signal that includes a DC signal and a third harmonic signal.

[0070] The U-phase complex vector Hu1(t) is expressed by the following equation (18) using the matrix A.

[0071]

number

[0072] The V-phase complex vector Hv1(t) is expressed by the following equation (19) using the matrix A.

[0073]

number

[0074] The W-phase complex vector Hw1(t) is expressed by the following equation (20) using the matrix A.

[0075]

number

[0076] The matrix A is expressed by the following equation (21).

[0077]

number

[0078] That is, in step S2, the processing unit 21 calculates a U-phase complex vector Hu1(t), a V-phase complex vector Hv1(t), and a W-phase complex vector Hw1(t) based on the following arithmetic expressions (22), (23), and (24).

[0079]

number

[0080] 10, the processing unit 21 calculates a first line Htop_uvt_w(t) that connects a vertex of a triangle 31, which has as one side a line connecting a vertex of the U-phase complex vector Hu1(t) and a vertex of the V-phase complex vector Hv1(t), to a vertex of the W-phase complex vector Hw1(t) (step S3). This step S3 corresponds to a third step, and the processing executed in step S3 corresponds to a third process. Note that the triangle 31, which has as one side a line connecting a vertex of the U-phase complex vector Hu1(t) and a vertex of the V-phase complex vector Hv1(t), may be an equilateral triangle or an isosceles triangle.

[0081] 10, the processing unit 21 calculates a second line Htop_vwt_u(t) by calculating a line connecting a vertex of a triangle 32 having as one side a line connecting a vertex of the V-phase complex vector Hv1(t) and a vertex of the W-phase complex vector Hw1(t) in the complex plane with a vertex of the U-phase complex vector Hu1(t) (step S4). This step S4 corresponds to a fourth step, and the processing executed in step S4 corresponds to a fourth process. Note that the triangle 32 having as one side a line connecting a vertex of the V-phase complex vector Hv1(t) and a vertex of the W-phase complex vector Hw1(t) may be an equilateral triangle or an isosceles triangle.

[0082] 10, the processing unit 21 calculates a third line Htop_wut_v(t) by calculating a line connecting a vertex of the V-phase complex vector Hv1(t) to a vertex of a triangle 33 having as one side a line connecting a vertex of the W-phase complex vector Hw1(t) to a vertex of the U-phase complex vector Hu1(t) (step S5). This step S5 corresponds to a fifth step, and the processing executed in step S5 corresponds to a fifth process. Note that the triangle 33 having as one side a line connecting a vertex of the W-phase complex vector Hw1(t) to a vertex of the U-phase complex vector Hu1(t) may be an equilateral triangle or an isosceles triangle.

[0083] Specifically, in step S3, the processing unit 21 calculates the first line Htop_uvt_w(t) based on the following equation (25), in step S4, the processing unit 21 calculates the second line Htop_vwt_u(t) based on the following equation (26), and in step S5, the processing unit 21 calculates the third line Htop_wut_v(t) based on the following equation (27).

[0084]

number

[0085] Next, the processing unit 21 calculates the intersection F(t) of the first line Htop_uvt_w(t), the second line Htop_vwt_u(t), and the third line Htop_wut_v(t) (step S6). This step S6 corresponds to the sixth step, and the processing executed in step S6 corresponds to the sixth process. As shown in FIG. 10, the intersection F(t) of the first line Htop_uvt_w(t), the second line Htop_vwt_u(t), and the third line Htop_wut_v(t) is different from the origin P0 of the complex plane. Specifically, in step S6, the processing unit 21 calculates the intersection F(t) based on the following arithmetic expressions (28) to (31).

[0086]

number

[0087] Then, as shown in FIG. 11, the processing unit 21 converts the intersection point F(t) into the origin P0 of the complex plane, thereby correcting the U-phase complex vector Hu1(t), the V-phase complex vector Hv1(t), and the W-phase complex vector Hw1(t) (step S7). This step S7 corresponds to the seventh step, and the processing executed in step S7 corresponds to the seventh process. Specifically, in step S7, the processing unit 21 corrects the U-phase complex vector Hu1(t), the V-phase complex vector Hv1(t), and the W-phase complex vector Hw1(t) based on the following arithmetic expressions (32) to (34). In FIG. 11 and the following arithmetic expressions (32) to (34), Hu2(t) is the corrected U-phase complex vector, Hv2(t) is the corrected V-phase complex vector, Hw2(t) is the corrected W-phase complex vector, Represents a phase complex vector.

[0088]

number

[0089] 12, the upper graph shows an example of the waveforms of the instantaneous value Hu0(t) of the U-phase sensor signal Hu, the instantaneous value Hv0(t) of the V-phase sensor signal Hv, and the instantaneous value Hw0(t) of the W-phase sensor signal Hw, over one electrical angle cycle. In FIG. 12, the middle graph shows an example of the waveforms of the real part of the U-phase complex vector Hu1(t), the real part of the V-phase complex vector Hv1(t), and the real part of the W-phase complex vector Hw1(t), over one electrical angle cycle. In FIG. 12, the lower graph shows an example of the waveforms of the imaginary part of the U-phase complex vector Hu1(t), the imaginary part of the V-phase complex vector Hv1(t), and the imaginary part of the W-phase complex vector Hw1(t), over one electrical angle cycle.

[0090] 13, the upper graph shows the norms of the U-phase complex vector Hu2(t), the V-phase complex vector Hv2(t), and the W-phase complex vector Hw2(t) obtained after the correction process of step S7 is performed. In FIG. 13, the middle graph shows the argument of the U-phase complex vector Hu2(t), the V-phase complex vector Hv2(t), and the W-phase complex vector Hw2(t) obtained after the correction process of step S7 is performed. In FIG. 13, the lower graph shows the phase difference θuv between the U-phase complex vector Hu2(t) and the V-phase complex vector Hv2(t), the phase difference θvw between the V-phase complex vector Hv2(t) and the W-phase complex vector Hw2(t), and the phase difference θwu between the W-phase complex vector Hw2(t) and the U-phase complex vector Hu2(t).

[0091] 13, the norms of the U-phase complex vector Hu2(t), the V-phase complex vector Hv2(t), and the W-phase complex vector Hw2(t) are the same. Furthermore, the phase difference θuv between the U-phase complex vector Hu2(t) and the V-phase complex vector Hv2(t), the phase difference θvw between the V-phase complex vector Hv2(t) and the W-phase complex vector Hw2(t), and the phase difference θwu between the W-phase complex vector Hw2(t) and the U-phase complex vector Hu2(t) are each 120 electrical degrees.

[0092] In this way, by performing the three-phase signal generation process, it is possible to obtain three-phase signals (U-phase complex vector Hu2(t), V-phase complex vector Hv2(t), and W-phase complex vector Hw2(t)) that have the same norm and a phase difference of 120 electrical degrees from each other. Furthermore, the U-phase complex vector Hu2(t), V-phase complex vector Hv2(t), and W-phase complex vector Hw2(t) are signals from which in-phase signals have been removed and from which mutual variations such as variations in amplitude values ​​and offset components have been corrected. In other words, by performing the three-phase signal generation process, it is possible to perform correction processes equivalent to the first correction process and the second correction process, and to obtain three-phase signals that have an accurate phase difference of 120 degrees.

[0093] By performing the above three-phase signal generation process, the processing unit 21 obtains the U-phase complex vector Hu2(t), the V-phase complex vector Hv2(t), and the W-phase complex vector Hw2(t), and then performs a third correction process on these three-phase signals having a phase difference of exactly 120 degrees. In this case, even if the third correction process is performed using the same table data on all curved portions (divided signals) included in the three-phase signals, it is possible to reduce errors caused by the positions of the divided signals.

[0094] The processing unit 21 performs a third correction process on the U-phase complex vector Hu2(t), the V-phase complex vector Hv2(t), and the W-phase complex vector Hw2(t), and then executes a learning process of the basic patent method to obtain the correspondence between the pole pair numbers, section numbers, and segment numbers, the characteristic data of each section, and the mechanical angle estimation formula of each segment, and stores the obtained data in the memory unit 22 as learning data.

[0095] The angle estimation process executed as online processing by the processing unit 21 in this embodiment is basically the same as the angle estimation process of the basic patent method. However, the processing unit 21 in this embodiment differs from the basic patent method in that, when executing the angle estimation process, it executes the above-mentioned three-phase signal generation process to obtain the U-phase complex vector Hu2(t), the V-phase complex vector Hv2(t), and the W-phase complex vector Hw2(t), and identifies the current section number and pole pair number based on these three-phase signals.

[0096] As described above, according to this embodiment, it is possible to obtain three-phase signals (U-phase complex vector Hu2(t), V-phase complex vector Hv2(t), and W-phase complex vector Hw2(t)) that have the same norm and a phase difference of 120 electrical degrees from each other. Therefore, according to this embodiment, the angle error between the estimated mechanical angle θ and the true mechanical angle can be further reduced compared to the basic patent method disclosed in Japanese Patent No. 6233532, thereby improving the accuracy of detecting the mechanical angle of the rotating shaft. Furthermore, according to this embodiment, by converting the three-phase sensor signals from instantaneous values ​​(real numbers) to complex vectors, a geometric approach (such as vector rotation and translation) is possible, and calculations can be easily performed on the complex plane without using elements that introduce signal delays, such as filters.

[0097] (Modifications) The present invention is not limited to the above-described embodiment, and the configurations described in this specification can be combined as appropriate within a range that does not contradict each other. For example, in the above-described embodiment, the combination of the motor 100 and the three-phase signal generator 1 is illustrated, but the present invention is not limited to this form, and a combination of a sensor magnet attached to a rotating shaft and the three-phase signal generator is also possible.

[0098] For example, in the above embodiment, the first magnetic sensor 11, the second magnetic sensor 12, and the third magnetic sensor 13 are arranged facing the disk-shaped sensor magnet 120 in the axial direction of the rotor shaft 110, but the present invention is not limited to this. For example, when a ring-shaped magnet is used instead of the disk-shaped sensor magnet, magnetic flux flows in the radial direction of the ring-shaped magnet, so the first magnetic sensor 11, the second magnetic sensor 12, and the third magnetic sensor 13 may be arranged facing the ring-shaped magnet in the radial direction of the ring-shaped magnet.

[0099] For example, in the above embodiment, the case where the sensor magnet 120 attached to the rotor shaft 110 of the motor 100 is used as the rotating magnet has been exemplified, but the rotor magnet attached to the rotor of the motor 100 may also be used as the rotating magnet. The rotor magnet is also a magnet that rotates in synchronization with the rotor shaft 110 and has multiple magnetic pole pairs.

[0100] In the above embodiment, the sensor group 10 includes three magnetic sensors 11, 12, and 13, but the number of magnetic sensors is not limited to three and may be N (N is a multiple of 3). Also, in the above embodiment, the sensor magnet 120 has four magnetic pole pairs, but the number of pole pairs of the sensor magnet 120 is not limited to four. Similarly, when a rotor magnet is used as a magnet for position detection, the number of pole pairs of the rotor magnet is not limited to four. [Explanation of symbols]

[0101] REFERENCE SIGNS LIST 1... Three-phase signal generating device, 10... Sensor group, 11... First magnetic sensor, 12... Second magnetic sensor, 13... Third magnetic sensor, 20... Signal processing unit, 21... Processing unit, 22... Storage unit, 100... Motor, 110... Rotor shaft, 120... Sensor magnet

Claims

1. a first magnetic sensor facing the rotating magnet and outputting a first signal indicating magnetic field strength; a second magnetic sensor facing the magnet and outputting a second signal having a phase delay of 120° in electrical angle with respect to the first signal; a third magnetic sensor facing the magnet and outputting a third signal having a phase delay of 120° in electrical angle with respect to the second signal; a signal processing unit that processes the first signal, the second signal, and the third signal, The signal processing unit a first process of digitally converting the first signal, the second signal, and the third signal to obtain instantaneous values ​​of the first signal, the second signal, and the third signal; a second process of calculating a first complex vector that is a complex vector of the first signal, a second complex vector that is a complex vector of the second signal, and a third complex vector that is a complex vector of the third signal, based on an instantaneous value of the first signal, an instantaneous value of the second signal, and an instantaneous value of the third signal; a third process of calculating, in a complex plane, a line connecting a vertex of the third complex vector to a vertex of a triangle having, as one side, a line connecting a vertex of the first complex vector to a vertex of the second complex vector; and a fourth process of calculating, in the complex plane, a line connecting a vertex of the first complex vector and a vertex of a triangle having, as one side, a line connecting a vertex of the second complex vector and a vertex of the third complex vector, as a second line; a fifth process of calculating, in the complex plane, a line connecting a vertex of the second complex vector and a vertex of a triangle having, as one side, a line connecting a vertex of the third complex vector and a vertex of the first complex vector, as a third line; a sixth process of calculating an intersection point between the first line, the second line, and the third line; and (7) a seventh process of correcting the first complex vector, the second complex vector, and the third complex vector by transforming the intersection point into an origin of the complex plane.

2. the signal processing unit calculates the first complex vector, the second complex vector, and the third complex vector based on arithmetic expressions (22), (23), and (24) in the second processing; 2. The three-phase signal generator according to claim 1, wherein Hu0(t) is an instantaneous value of the first signal, Hv0(t) is an instantaneous value of the second signal, Hw0(t) is an instantaneous value of the third signal, Hu1(t) is the first complex vector, Hv1(t) is the second complex vector, and Hw1(t) is the third complex vector. [Equation 1]

3. the signal processing unit calculates the first line based on an arithmetic expression (25) in the third processing, calculates the second line based on an arithmetic expression (26) in the fourth processing, and calculates the third line based on an arithmetic expression (27) in the fifth processing; 3. The three-phase signal generator according to claim 2, wherein Htop_uvt_w(t) is the first straight line, Htop_vwt_u(t) is the second straight line, and Htop_wut_v(t) is the third straight line. [Equation 2]

4. the signal processing unit calculates the intersection point based on arithmetic expressions (28) to (31) in the sixth process; 4. The three-phase signal generating device of claim 3, wherein F(t) is the intersection point. [Equation 3]

5. the signal processing unit corrects the first complex vector, the second complex vector, and the third complex vector based on arithmetic expressions (32) to (34) in the seventh processing; 5. The three-phase signal generator according to claim 4, wherein Hu2(t) is the first complex vector after correction, Hv2(t) is the second complex vector after correction, and Hw2(t) is the third complex vector after correction. [Equation 4]

6. a first magnetic sensor facing the rotating magnet and outputting a first signal indicating magnetic field strength; a second magnetic sensor facing the magnet and outputting a second signal having a phase delay of 120° in electrical angle with respect to the first signal; a third magnetic sensor facing the magnet and outputting a third signal having a phase delay of 120° in electrical angle with respect to the second signal, a first step of digitally converting the first signal, the second signal, and the third signal to obtain instantaneous values ​​of the first signal, the second signal, and the third signal; a second step of calculating a first complex vector that is a complex vector of the first signal, a second complex vector that is a complex vector of the second signal, and a third complex vector that is a complex vector of the third signal based on the instantaneous value of the first signal, the instantaneous value of the second signal, and the instantaneous value of the third signal; a third step of calculating, in a complex plane, a line connecting a vertex of the third complex vector and a vertex of a triangle having a line connecting a vertex of the first complex vector and a vertex of the second complex vector as one side, as a first line; a fourth step of calculating, in the complex plane, a line connecting a vertex of the first complex vector and a vertex of a triangle having, as one side, a line connecting a vertex of the second complex vector and a vertex of the third complex vector; and a fifth step of calculating, in the complex plane, a line connecting a vertex of the second complex vector and a vertex of a triangle having, as one side, a line connecting a vertex of the third complex vector and a vertex of the first complex vector, as a third line; a sixth step of calculating an intersection point of the first line, the second line, and the third line; and a seventh step of correcting the first complex vector, the second complex vector, and the third complex vector by transforming the intersection point to the origin of the complex plane.

7. In the second step, the first complex vector, the second complex vector, and the third complex vector are calculated based on the arithmetic expressions (22), (23), and (24), 7. The three-phase signal generation method according to claim 6, wherein Hu0(t) is an instantaneous value of the first signal, Hv0(t) is an instantaneous value of the second signal, Hw0(t) is an instantaneous value of the third signal, Hu1(t) is the first complex vector, Hv1(t) is the second complex vector, and Hw1(t) is the third complex vector. [Equation 5]

8. In the third step, the first straight line is calculated based on an arithmetic expression (25), in the fourth step, the second straight line is calculated based on an arithmetic expression (26), and in the fifth step, the third straight line is calculated based on an arithmetic expression (27), 8. The three-phase signal generating method according to claim 7, wherein Htop_uvt_w(t) is the first straight line, Htop_vwt_u(t) is the second straight line, and Htop_wut_v(t) is the third straight line. [Equation 6]

9. In the sixth step, the intersection point is calculated based on the formulas (28) to (31), 9. The method of claim 8, wherein F(t) is the intersection point. [Equation 7]

10. In the seventh step, the first complex vector, the second complex vector, and the third complex vector are corrected based on the arithmetic expressions (32) to (34), 10. The three-phase signal generating method according to claim 9, wherein Hu2(t) is the corrected first complex vector, Hv2(t) is the corrected second complex vector, and Hw2(t) is the corrected third complex vector. [Equation 8]

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